1. Field of the Invention
This invention relates to a method and apparatus for finishing the end faces of optical fibers, and in particular to a method and apparatus for both preparing the end face of an optical fiber and terminating the fiber and its outer jacket with a suitable termination ferrule or the like.
2. Description of the Prior Art
Optical fibers, i.e., thin fibers of optical plastic, glass, or silica, having diameters ranging from about 5 to 250 micrometers, are well known in optical communication systems. In such systems, low light-loss connections are desirable to join two light transmitting cables of optical fibers or to terminate a light transmitting cable on a chassis or terminal board. To optimize light coupling efficiency, the end face, or end surface, of each film must be smooth, with a surface configuration (flat, convex, or concave) that is symmetrical about the fiber's axis.
Typically, the fiber end face is prepared by grinding and polishing or by scribing and breaking. The scribe and break technique, properly executed, yields flat and smooth end surfaces, but does not reliably yield surfaces that are exactly perpendicular to the fiber's axis. Grinding and polishing, on the other hand, can yield flat, perpendicular surfaces (U.S. Pat. No. 4,135,781) but does not readily lend itself to the production of convex or concave surfaces. The desired smoothness is achieved by using extremely small-size polishing grit. However, grinding and polishing are slow and costly. The degree of polish and, consequently, the amount of light-loss vary considerably, depending on operator skill and equipment.
Another method that has been used to prepare the face of an optical fiber involves using an electric arc discharge to melt the tip of the fiber and form a "bead." This method has the drawback that the size and position of the bead depend on parameters that are difficult to control, such as arc temperature, ambient relative humidity, and the shape of the initial break.
U.S. Pat. No. 4,147,402, issued Apr. 3, 1979, to M. Chown, discloses a process for manufacturing a lens termination for an optical fiber using laser machining to form a cavity which centers the fiber in the termination. However, in that process, the laser acts only on a plastic preform and does not affect the fiber end face.